Neutral Axis

Gutter Stuff review (2 years in place)

by on Jul.08, 2013, under Uncategorized

Two years ago I saw a product at Sam’s Club called Gutter Stuff.  It was a wedge shaped piece of black foam that was to be placed in a gutter and claimed to keep debris out of the gutter while allowing water to flow through nearly unimpeded.  I recall it running about $2 a foot in a 24′ box of 3′ lengths, so did a section of my gutter and was please enough with it’s performance that I went back and got enough to do the whole house.  I’ve since seen it available online and at Home Depot.  It’s been two years, and the stuff isn’t perfect, but it’s pretty good.  Here’s my review.

Gutter Stuff cross section

First of all, like the photo shows, it’s a wedge of non-absorbant black foam.  Very open celled.  And sure enough, you can turn a hose onto it and it pours right through.  Where there are long straight sections of gutter on my house, it has done a very good job of keeping debris out and water never runs over the top.  When I recently removed a section, all that was laying in the gutter underneath was a bit of fine dirt and some granules that had washed off the shingles.  Not a single leaf or even seed had made it through.  And as per the advertisement, when leaves and seeds collect on top, they dry out and eventually blow away. (Midwest Climate on a heavily wooded lot)

There’s one situation however, which occurs in about 4 locations on my house where water commonly will spill over the top of the gutter during a very heavy rain.  That has been where there are valleys in the roof that concentrate water into a single spot.  If too much debris is there, it can overtop.  I’ve corrected that for the most part, but putting up “gusher guards” which are sheet metal pieces that are commonly used to deflect the water to the sides.  And where that concentration is far away from the downspout, a different problem causes overtopping.

Like I said earlier, a hose directed at the foam will pour right through.  A couple of inches thickness of foam doesn’t impede the water hardly at all.  However, 20 feet of it can.  What I mean by that, is where there is a concentrated stream of water pouring into the gutter 20 feet away from the downspout, that water has to flow through 20 feet of foam to reach the downspout.  Despite the wedge shape, there simply isn’t enough free area remaining to handle concentrated flow during a really heavy rain.  I discovered this was the problem when I donned a raincoat during a heavy rain and climbed a ladder to see what was happening.  From the high end to the low end, the gutter falls about an inch.  During this rain event, it was overtopping the gutter at the high end where the concentrated flow entered, yet was only about 1/2″ deep at the low end near the downspout.  The water wasn’t running across the top of the foam.  Instead it had completely filled the gutter and was running over the top.  So if you could have measured the water surface from the ground, the surface at the high end was 3.5″ above the surface at the low end.  In engineering, that’s referred to as the hydraulic gradient.  Considering that water wants to be level, and unimpeded will flow at about the same depth at all locations in a sloped channel, that indicated to me that the foam was causing a significant impediment to flow down the length of the gutter.

Water surface diagrammatic

My solution, which worked well during a heavy rain over the weekend, is that I have removed all the foam and reshaped it with a utility knife, from a wedge shape to an L shape.  Doing so has created more unrestricted flow area, and during the last heavy rain event, it didn’t overtop.  It also seems to still have enough rigidity to it that it is holding in place without sagging.  See the photo below of a newly shaped piece.

2013-07-06 17.13.12

Wedge shape cut into an L shape

Installation tip 1:  If you gutter is supported like mine with a spike every few feet, use a utility knife and cut sections of the foam to fit between them.  It’s too difficult to try to get them wedged underneath the spikes.

Installation tip 2:  If you reshape your foam as I’m suggesting, squeeze the legs together and insert them into the gutter at the same time, push the top corner back under the leading edge of the shingles and then pull the top surface leg back up.  This will ensure that the back leg is standing vertically at the rear of the gutter like in the picture.


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